Field of the Invention
The present invention relates to an electrophotographic photosensitive member and a manufacturing method thereof, a process cartridge and an electrophotographic apparatus, and a phthalocyanine crystal and a manufacturing method thereof.
Description of the Related Art
An electrophotographic photosensitive member for use in an electrophotographic apparatus such as a copier and a laser beam printer is required to have sufficient sensitivity to the light for image exposure. It is known that an azo pigment and a phthalocyanine pigment for use as a charge generating substance have high sensitivity to the light in a wide range of wavelength.
A higher quality image typically including a colored image has been increasingly required in recent years, with increased demand for a half-tone image and a solid image of a photograph, as a typical example. The allowable range, for example, for a so-called positive ghost image, i.e. a phenomenon that an area exposed to light in a sheet of image has high density in a half-tone image, has been distinctly severer in comparison with the allowable range for a monochrome printer or a monochrome copier. It is presumed that the ghost images occur because electrons tend to remain in the charge generation layer to make a memory after injection of positive holes as one of carriers generated from a charge generating substance.
In Japanese Patent Application Laid-Open No. H07-331107, a hydroxygallium phthalocyanine crystal including at least one polar organic solvent selected from the group consisting of a compound having an amide group, a compound having a sulfoxide group, and an organic amine is disclosed.
In Japanese Patent Application Laid-Open No. 2002-235014, a hydroxygallium phthalocyanine crystal obtained by milling treatment using N-methylformamide, N-methylacetamide, and N-methylpropionamide is disclosed.